Bacterial acquisition of antimicrobial resistance (AMR) via horizontal gene transfer (HGT) has contributed to the rise in superbugs. Although there are multiple known mechanisms used by bacteria to transfer AMR, a less explored mechanism involves membrane vesicles (MVs). MVs are released by all bacteria as part of their normal growth and are rich in DNA. In this study, we examined the ability of MVs produced by pathogens and the human gut microbiome to contribute to HGT and the spread of AMR.
We found that Pseudomonas aeruginosa and Escherichia coli MVs contained DNA encoding for AMR genes, and that antibiotic treatment increased MV production. Furthermore, MVs containing AMR genes could mediate HGT resulting in antibiotic-resistant transformants, highlighting the ability of MVs to facilitate HGT.
The human gut microbiome is a reservoir for AMR where HGT can occur. However, the ability of MVs to contribute to HGT of AMR within the human gut microbiome remains unknown. Therefore, we next investigated the ability of microbiota-derived MVs to contain AMR and mediate HGT. We purified MVs from a mixed microbiome culture consisting of 95 isolates obtained from the gut of healthy individuals. We found that sub-lethal doses of antibiotics increased MV production by these cultures, with increased packaging of nucleic acids. We are currently sequencing the DNA within microbiota-derived MVs to determine whether they contain AMR genes, and are investigating their ability to mediate HGT. Collectively, these studies will advance our limited knowledge regarding the contribution of MVs to AMR in a physiological setting.